Massive swaths of people swarmed the streets outside the Hong Kong government headquarters this weekend to demand election reform. A crackdown ensued: Police pepper sprayed the protesters and hurled tear gas canisters into the peaceful demonstration.

“This is already much bigger than anything the Beijing or Hong Kong authorities expected,” Larry Diamond, a senior fellow and democratic development scholar at the Hoover Institution at Stanford University, told the New York Times.

Attempts by government officials to disperse the protesting masses—the majority students—from a major thoroughfare in the heart of Hong Kong appeared to only prompt others to join the demonstration. On Monday evening, the streets outside the government headquarters were jam-packed, awash with pro-democracy protesters.

Unrest in Hong Kong, the former British colony and a global financial center, stems from controversy surrounding the interpretation of the city’s mini-constitution, the Basic Law. How Hong Kong’s top leader, the chief executive, becomes elected is the main point of contention.

Currently, this post is chosen by a “broadly representative nominating committee.” But, members of the Chinese legislature recently ruled that, in order to be on the ballot, candidates need more than half the votes of the nominating committee, which consists mainly of Beijing loyalists. Fuller democratic elections are thus the protesters’ aim.

Chinese President Xi Jinping’s tenure has been marked by strong opposition to political liberalization and public demonstrations, but how he and the Communist Party will react to the student-led protests is still unclear.